Foldable module with locking mechanism. Foldable module with locking mechanism. (A to C) Foldable structure using Sarrus linkage. (D to F) Locking mechanism by adjusting the shape of the Sarrus linkage and adding an extra facet. (A) Deployed state. The Sarrus linkage with four chains assumes a square column shape when deployed. (B) Transition state. (C) Folded state. The Sarrus linkage can be folded flat when the two links are of the same length. (D) In the locked mode, the fold line p to r cannot be folded because the lockers are in the locked position. The locking mechanism constrained the degrees of freedom of the foldable module and increased its stiffness. (E) Locker in the transitional position. (F) In the foldable mode, the lockers are in the unlocked position. The lockers were unlocked from the U1-B1 facet and overlapped with U2. Because all facets were in the same plane, the fold line p to r could be folded. Upper figures depict trimetric views of the module. The figure shows only the frontal two chains for simplicity. Lower figures depict a top view of the module. Suk-Jun Kim et al. Sci. Robotics 2018;3:eaar2915 Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works